A transcranial electrical stimulation method is a method for electrically stimulating the motor area of a cerebral cortex. The method was reported by Levy et al. in 1984 (Levy, 1984), and at the same time, the method was immediately spread all over the world.
The transcranial electrical stimulation method is widely used mainly for the purpose of spinal cord lesion segment diagnosis in a spinal cord disorder or for performing spinal cord function monitoring during surgery of a spinal cord tumor and the like (Mckay, 1997). Since spinal cord lesion segment diagnosis can functionally diagnose the lesion segment of the spinal cord disorder, the certainty of the treatment was dynamically improved.
When there is a danger of causing a spinal cord injury during a surgery of an intramedullary spinal cord tumor, scoliosis and the like, spinal cord function monitoring is essential for performing the surgery safely.
Regarding spinal cord lesion segment diagnosis or spinal cord function monitoring, there are many reports discussing its usefulness. With regard to the Applicant of the present application, there are 600 cases which had performed the transcranial electrical stimulation method in the past 12 years. When considering that there are approximately 4500 orthopedic hospitals in Japan, it is presumed that the number of cases in which the present method has been performed is large.
However, on the contrary, there also are problems such as the following.
In the conventional method, in order to stimulate the motor area of the cerebral cortex, the skull outer layer which is directly thereon is bored with a drill and a hole is made to mount a needle electrode.
Although there is no serious report for complications up till now in the conventional method, time was required to mount the electrode since the bone had to be bored.
Since there are personal differences in head size, it does not necessarily mean that an effective motor area of a cerebral cortex can be stimulated at the first electrode mounting. If an emission of an evoked potential is difficult, there are cases where a change in the electrode position is needed.
Therefore, a development is desired for a mounting means of an electrode which is more easily mountable to the head and is also minimally invasive.
Japanese Laid-Open Publication No. 9-294815 (Reference 1) discloses a transcranial electrical stimulation device for outputting currents which are independently adjusted, respectively, from two electrode pairs.
However, in this device, the electrodes are attached to the head by a band and the like. The electrodes cannot be accurately positioned to predetermined positions of a patient's head.
Japanese Laid-Open Publication No. 7-289649 (Reference 2) discloses a stimulant signal generating device of an ophthalmic nerve for generating nervous waves in which there is less weariness and the effect of the treatment is improved. However, this subject matter does not relate to a transcranial electrical stimulation device.
Japanese Laid-Open Publication No. 2003-339885 (Reference 3) discloses an electrical stimulating device for activating scalp capable of preventing the deterioration of scalp tissues, and reducing headache and symptoms accompanying therewith, by alleviating the abnormal tension of head part facial muscles. However, this subject matter also does not relate to a transcranial electrical stimulation device.    Reference 1: Japanese Laid-Open Publication No. 9-294815    Reference 2: Japanese Laid-Open Publication No. 7-289649    Reference 3: Japanese Laid-Open Publication No. 2003-339885